Manufacture of artificial silk from viscose



Patented Apr. 13, 1926.

UNITED STATES 1,580,843- PATENT OFFICE.

WILLIAM MENDEL, OF BEVERLY, NEW JERSEY, ASSIGNOR TO SAMUEL A. NEIDICH,O1 EDGEWATER PARK, NEW JERSEY.

MANUFACTURE OF ARTIFICIAL SILK FROM VISCOSE.

No Drawing.

To all whom it may concern:

Be it known that 1, WILLIAM MENDEL, a citizen of the United States,residing at Beverly, in the county of Burlington and State of NewJersey, have invented a certain new and useful Improvement in theManufacture of Artificial Silk from Viscose, whereof the following is aspecification.

llgy invention relates to the manufacture of aments projectin viscose(variously known as ce ulose sulphocarbonate or cellulose thiocarbonate)through minute spinneret orifices into baths containing chemicals whichcoagulate the viscose as a semisolid impure cellulose hydrate, whichmust be subjected to subsequent cleaning processes and thereafter driedto form the commercial artificial silk.

Natural silk filaments have an average diameter of .015 millimeter and,therefore, its is highly desirable to produce artificial silk filamentsof approximately the same diameter. However, the aforesaid coagulatedviscose elements must, of course, be of sufiicient strength to withstandthe stresses of manipulation incident to their production, and as theviscose products of ordinary processes are much weaker and morefrangible than the natural silk filaments; it has been found impossibleto commercially manufacture viscose silk filaments which are less thandouble the diameter of the natural silk filaments. For instance, ifdried in air, the minimum diameter of ordinary viscose silk filaments is.03051 millimeter and if viscose silk filaments are subjected to theaction of glycerine, as is usual to improve their flexibility, theminimum ultimate diameter attainable is .03545 millimeter.

Therefore, an object and effect of my invention is to provide a methodand means for commercially producing viscose silk filaments as fine,lustrous and elastic as natural silk filaments.

Various chemicals are used in the precipitating bath aforesaid. Forinstance, because of their prom t action and relatively low cost, strongacid baths, such as aqueous solutions containing eight percent ofsulphuric acid or five percent of hydrochloric acid, are commonly used.With baths of that character, substantially all of the sulphur rimarilychemically combined with the cellulose in viscose is released as freesulphur, but is occluded in the mass of Application filed m 28, 1925.Serial No. 33,502.

cellulose hydrate, causing the latter to present an undesirable dullyellow white appearance, whereas, natural silk has a characteristiclustrous, translucent appearance. Therefore, such ordinary processes ofcoagulation must be supplemented by successive treatments of thecoagulated viscose in chemical baths with a view to removal of thesulphur impurities therefrom. However, although such cleansingoperations are only partially successful, they leave the viscosefilaments weak, brittle and inelastic as compared with natural silk.

Microscopic examination of such ordinary viscose silk filamentsdiscloses that their inherent weakness as compared with natural silkfilaments is due to the fact that whereas, a natural silk filament is ofsubstantially uniform homogeneous solid structure with a smoothlycontinuous surface; an ordinary viscose filament is of porous structurewith a pitted surface; the formation of such pores and pits beingincident to the primary inclusion and occlusion of sulphur derivativesin the cellulose hydrate and subsequent partial elimination of the same,leaving the cellulose hydrate of spongy texture.

Therefore, an object and effect of my invention is to provide a methodand means for commercially producing viscose silk filaments withoutoccluding free sulphur or its derivatives therein and to thus strengthenthe coagulated cellulose hydrate filament by the elimination of poresand pits as aforesaid, and it is the attainment of that result whichpermits the formation of filaments, in accordance with this invention,as fine as natural silk filaments.

I have discovered that the desirable results aforesaid are attainable bysubjecting viscose to the action of P0 ions. Such ions have a beneficialeffect if added to or formed in the viscose, or in any bath in which viscose may be coagulated, or in a fluid distinct from either the viscoseor the coagulating medium, and in the latter case, may be either aloneor in association with other matter affecting the viscose complex. Forinstance, the impure cellulose hydrate roduct of coagulation of viscosemay be su jec-ted to P0 ions in a fluid containing dyeing material ordetergent material.

PO ions have the apparent effect of preventing the formation of sulphuror its derivatives in insoluble form, and thus render the coagulatedproducts ractically selfcleansing. However, if P 4 ions be added to orformed in the viscose before coagulating the same in the form offilaments, they have the effect of accelerating the regressive aging ofthe viscose which 1s manifested by progressive increment in viscosity ofthe viscose which may or not be desirable in accordance with the processof coagulation to which the viscose is to be subjected. However, in theform of my invention herein contemplated, I prefer to subject theviscose to the action of PO, ions in a bath in which the viscose ispresented in the form of filaments; so that the aforesaid a 'ng effectof the P0 ions upon the uncoagu ated mass of viscose is avoided, but theviscose filament is beneficially affected by the P0 ions immediatelyupon introduction to such bath, and thus immediately strengthened towithstand the stresses to which it is subjected, in its pro ion throughand from the bath. The P 4 ions may be added to or produced in such bathin any convenient form or manner. However, tri-sodium phosphate (Na POQis a cheap vehicle for such ions and is further preferable because itmay be conveniently used in aqueous solution.

In the form of my invention herein claimed; the vicose filament issubjected to a preliminary coagulating medium which is an acid salt. Forinstance, an aqueous solution containing sodium bi-sulphite (NaHSO,,)and salammoniac (ammonium chloride NILCL), and containing twenty-fiveper cent of the former and ten per cent of the latter. Such a bathpromptly coagulates the viscose to an impure cellulose hydrate complexsufliciently coherent to be mechanically drawn through and from suchbath over a roller. However, in the absence of P0 ions, such coagulatedproduct contains the objectionable free sulphur and its derivativesabove contemplated.

However, such complexes are rendered soluble and eliminated from thefilament by subsequent subjection of the latter to the action of thebath containing PO, ions; which may be merely water containing three ercent orless of tri-sodium phosphate. I d that the presence of even afraction of one per cent of PO, ions in such a bath has the advantageousresults above contemplated, in the elimination of insoluble derivativesin or upon the filaments projected therein.

Filaments thus coagulated in accordance with my invention may require nosubsequent treatment other than rinsing with water, as they arepractically self-cleansing, in such PO ion bath, and emerge therefrom ofsubstantially uniform homogeneous structure and with smooth surfaces.When such filaments are dried, preferably under tension, they haveunusually high luster, strength in the appended claims.

I claim:

1. The method of manufacturin artificial silk filaments from viscosewhic consists in coagulating viscose by pro ecting a fine filamentthereof into a soft coagulating medium and thence into an ,aqueoussolution containing PO, ions.

2. The method of manufacfiirin artificial silkfilaments from viscosewhich consists in coagulating viscose by projecting a fine filamentthereof into a salt coagulating medium and thence into an aqueoussolution containing PO, ions associated with other ions capable ofafl'ecting such 00- agulation.

3. The method of manufacturin artificial silk filaments from viscosewhich consists in coagulating viscose by projecting a fine filamentthereof into a salt coagulating medium and thence into an aqueoussolution containing PO, ions, resultant from inclusion of tri-sodiumphosphate (Na PO in such solution.

4. The method of manufacturin artificial silk filaments from viscosewhich consists in coagulating viscose by projecting a fine filamentthereof into a salt coagulating medium and thence into an aqueoussolution containing PO, ions, resultant from inclusion of tri-sodiumphosphate (Na,PO,) in such solution, with another solute capable ofafl'ectin such coa lation.

5. The metho of manu actuiing artificial silk from viscose whichconsists in projecting a filament of the latter into an aqueous solutioncontaining sodium bi-sulphite (NaHsO and thence into an aqueous solutionin which tri-sodium phosphate (Na,PO,) has been dissolved.

6. The method of manufacturing artificial silk which consists inprojecting a filament of viscose (thiocarbonate) through an orifice lessthan .025 millimeter in diameter, into a salt coa lating bath, retainingsaid filament in said bath until partly coagulated, and thenceprojecting said filament into a bath containing PO ions.

7. The method of manufacturing artificial silk filaments from viscose byprojecting a fine filament thereof into an acid salt coagulating mediumcomprising an aqueous solution containing twent -five percent of sodiumbi-sulphite (NaH 0,) and ten ercent of ammonium chloride (NH retainingsaid filament in said coa ulating medium until partly coagulated, anthence projecting said filament into a bath containing PO ions.

8. The method of manufacturing artificial silk filaments from viscose byproject ing a fine filament thereof into an acid salt coagulating mediumcomprising an aqueous solution containing twenty-five percent of sodiumbi-sulphite (NaHSO and ten percent of ammonium chloride (NH CL); re-

taining said filament in said ooa medium until artly coagulate], an:thence projecting sai filament into a bath containing PO ions derivedfrom aqueous solution of tri-sodium phosphate (Na POJ.

In testimony whereof, I have hereunto signed my name at Burlington, NewJersey, this 20th day of May, 1925.

WILLIAM MENDEL.

lating 10 projecting said filament into a bath containing PO ions.

8. The method of manufacturing artificial silk filaments from viscose byprojecting a fine filament thereof into an acid salt coagulating mediumcomprising an aqueous solution containing twenty-live percent of sodiumbi-sulphite (NaHSO and ten percent of ammonium chloride (NH CL); re-

taining said filament in said coa lating 10 medium until artlycoagulated, am thence projecting sai filament into a bath containing POions derived from aqueous solution of tri-sodium phos hate (Na PO Intestimony Whereo I have hereunto signed my name at Burlington, NewJersey, this 20th day of Ma 1925.

W LLIAM MENDEL.

Certificate of Correction. It is hereby certified that in Letters PatentNo. 1,580,843, fainted April 13, 1926,

GI'SG upon the a plication of William Mendel, of Beverly e Manufactureof Artificial Silk from ment in New for an improve- Viscose,

errors a pear in the printed specification requiring correction asfollows: Page 1i line 21, or the word its read it; page 2, line 79,claim 1, for the word soft rea salt; and that the said Letters Patentshould be read with these corrections therein that the same may conformto the record of the case in the Patent Ofiiee.

Signed and sealed this 4th day of May, A. D. 1926.

' M. J. MOORE Acting Commissioner of Patents.

Certificate of Correction.

It is hereby certified that in Letters Patent No. 1,580 843, gnintedApril 13, 1926, upon the a Fplication of William Mendel, of Beverly IiewJersey, for an improvement in he Manufacture of Artificial Silk fromViscose, errors a pear in the printed specification requiring correctionas follows: Page 1, line 21, or the word its read it; page 2, line 79,claim 1, for the word soft read salt; and that the said Letters Patentshould be read with these corrections therein that the same may conformto the record of the case in the Patent Ofiioe.

Slgned and sealed this 4th day of May, A. D. 1926.

[sun] v M. J. MOORE,

Acting C'mwmiasz'oner of Patents.

